CA2129915C - Device and method for detection of leaks in pressurized fluid vessels - Google Patents
Device and method for detection of leaks in pressurized fluid vesselsInfo
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- CA2129915C CA2129915C CA002129915A CA2129915A CA2129915C CA 2129915 C CA2129915 C CA 2129915C CA 002129915 A CA002129915 A CA 002129915A CA 2129915 A CA2129915 A CA 2129915A CA 2129915 C CA2129915 C CA 2129915C
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- 239000012530 fluid Substances 0.000 title claims abstract description 19
- 238000000034 method Methods 0.000 title claims description 24
- 238000001514 detection method Methods 0.000 title description 9
- 230000008859 change Effects 0.000 claims abstract description 51
- 238000005259 measurement Methods 0.000 claims description 20
- 238000012544 monitoring process Methods 0.000 claims description 12
- 238000005070 sampling Methods 0.000 claims description 4
- 230000009471 action Effects 0.000 claims description 3
- 230000000694 effects Effects 0.000 claims 2
- 230000000977 initiatory effect Effects 0.000 claims 1
- 238000012360 testing method Methods 0.000 abstract description 11
- 230000001788 irregular Effects 0.000 abstract description 3
- 238000013480 data collection Methods 0.000 abstract description 2
- 239000000463 material Substances 0.000 description 3
- 230000035945 sensitivity Effects 0.000 description 3
- 230000005494 condensation Effects 0.000 description 2
- 238000009833 condensation Methods 0.000 description 2
- 238000005260 corrosion Methods 0.000 description 2
- 230000007797 corrosion Effects 0.000 description 2
- 230000006870 function Effects 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 206010035148 Plague Diseases 0.000 description 1
- 241000607479 Yersinia pestis Species 0.000 description 1
- 238000009530 blood pressure measurement Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- GWUSZQUVEVMBPI-UHFFFAOYSA-N nimetazepam Chemical compound N=1CC(=O)N(C)C2=CC=C([N+]([O-])=O)C=C2C=1C1=CC=CC=C1 GWUSZQUVEVMBPI-UHFFFAOYSA-N 0.000 description 1
- 230000008439 repair process Effects 0.000 description 1
- 230000000007 visual effect Effects 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M3/00—Investigating fluid-tightness of structures
- G01M3/02—Investigating fluid-tightness of structures by using fluid or vacuum
- G01M3/26—Investigating fluid-tightness of structures by using fluid or vacuum by measuring rate of loss or gain of fluid, e.g. by pressure-responsive devices, by flow detectors
- G01M3/28—Investigating fluid-tightness of structures by using fluid or vacuum by measuring rate of loss or gain of fluid, e.g. by pressure-responsive devices, by flow detectors for pipes, cables or tubes; for pipe joints or seals; for valves ; for welds
- G01M3/2807—Investigating fluid-tightness of structures by using fluid or vacuum by measuring rate of loss or gain of fluid, e.g. by pressure-responsive devices, by flow detectors for pipes, cables or tubes; for pipe joints or seals; for valves ; for welds for pipes
- G01M3/2815—Investigating fluid-tightness of structures by using fluid or vacuum by measuring rate of loss or gain of fluid, e.g. by pressure-responsive devices, by flow detectors for pipes, cables or tubes; for pipe joints or seals; for valves ; for welds for pipes using pressure measurements
Abstract
A device (10) for detecting irregular operation in a pressurized fluid vessel, such as leaks in a pipeline (20), includes a transducer (21) for measuring pipeline (20) instantaneous pressure, a microcomputer (23) and a wake-up timer (29). Microcom-puter (23) performs several different tests upon the collected pressure data to reliably ascertain if a leak or break in pipeline (20) has occurred. The first test involves a comparison of rates of change of pressure at successive preselected timed intervals, referred to as timed interval comparisons. If any test is failed, an alarm (30) and/or actuator (31) for valve or system sllut-down are operated. Once the timed intervals and testing are concluded, microprocessor (23) reverts to a powerdown mode to con-serve power. Wake-up timer (29) resets microcomputer (23) at preselected intervals for additional pressure data collection and testing.
Description
2~299t5 DEVICE AND METHOD FOR
DETECTION OF LEAKS IN PRESSURIZED FLUID VESSELS
TECHNICAL FIELD
The present invention relates generally to a device and method for detecting irregular operation in pressurized fluid vessels carrying liquid or gaseous materials.
More particularly, the invention relates to electronic instrumentation and methods of operation for detecting leaks in a pipeline. Still more specifically, the present invention relates to electronic pipeline leak detectors in which instantaneous ples~ule magnitudes are monitored, and values such as average rate of change of pressure and maximum change of pressure are calculated and compared with preselected values, providing an indication of potential leaks or breaks in the pipeline so that an alarm annunciation or action can be taken, if necessary or desired.
BACKGROUND ART
Leaks or breaks in a vessel, such as a pipeline, that can be transporting a fluid or gaseous material over long distances, must be detected in order to avoid loss of the material, and, in many cases, for safety and environmental considerations. Moreover, many such pipeline vessels are located in outlying areas witl1 no on-site attendant, and thel-erore a reliable device and method for remote detection is necessary and desirable.
If, on the other hand, such devices and methods indicate erroneously that a leakor break has occurred, a false alarm is sounded. False alarms can be expensive to the pipeline operator, as they could cause false shut-downs of the pipeline and/or unneces-sary repair trips by maintenance persolmel. Therefore, while it is desirable to provide a device and method that is sensitive to detection of those vessel characteristics whose magnitude change upon the occurrence o~ a leak or break (such as pres~ule, flow and tel~per~lule), care must be taken to preclude false detection possibilities.
Currently available leak detection devices, such as the pressure based sensing device disclosed in U.S. Patent No. 4,012,944, can be sensitive enough to detect most unacceptable operational conditions, but they do not have an accurate method of determining if the unacceptable condition results from something other than a leak or break, and therefore the potential for false alarms exists. Devices as this measure pressure and calculate both rate of pressure change and total pressure cllange, and from these measurements determine if a leak or break has occurred.
Moreover, most commercially available devices for detection of pipeline leaks or breaks are at least in part mechanical in nature, often giving rise to such problems as a lack of sufficient sensitivity, and greater susceptibility to corrosion, condensation and blockage.
Comparison of rates of change at successive preselected timed intervals has beenfound to greatly facilitate recognition of instances of false triggering and theavoidance of false alarms without the sacrifice of sufficient sensitivity to detect substantially all leaks and breaks, particularly when utilized in conjunction with known leak and break detection techniques. Also, this method of operation may beimplemented wholly electronically, avoiding the difficulties that may plague devices with mechanical components, and using any desired characteristic, of course including the most common characteristic of pressure.
SUMMARY OF THE INVENTION
It is, therefore, an object of the present invention to provide a device and method for detecting leaks or breaks in pressurized fluid vessels, such as a pipeline, which minimi7.es or elimin~tes false alarms.
It is another object of the present invention to provide a device and method, asset forth above, that measures a cllaracteristic that changes upon the occurrence of a break or leak, determines the rate of change of such characteristic at preselected times, and compares the rates of change at successive preselected timed intervals.
It is yet another object of the present invention to provide a device and method, as set forth above, that also determines the total change, and minimum and maximum magnitudes of such characteristic in the vessel over a preselected period of time.
It is still another object of the present invention to provide a device and method, as set forth above, that may be implemented electronically so as to enhance sensitivity and minimi7.~. or eliminate susceptibility to corrosion, condensation and blockage.
It is a further object of the present invention to provide a device and method, as set forth above, that utilizes pressure as the characteristic from which determinations as to leaks or breaks is made.
DETECTION OF LEAKS IN PRESSURIZED FLUID VESSELS
TECHNICAL FIELD
The present invention relates generally to a device and method for detecting irregular operation in pressurized fluid vessels carrying liquid or gaseous materials.
More particularly, the invention relates to electronic instrumentation and methods of operation for detecting leaks in a pipeline. Still more specifically, the present invention relates to electronic pipeline leak detectors in which instantaneous ples~ule magnitudes are monitored, and values such as average rate of change of pressure and maximum change of pressure are calculated and compared with preselected values, providing an indication of potential leaks or breaks in the pipeline so that an alarm annunciation or action can be taken, if necessary or desired.
BACKGROUND ART
Leaks or breaks in a vessel, such as a pipeline, that can be transporting a fluid or gaseous material over long distances, must be detected in order to avoid loss of the material, and, in many cases, for safety and environmental considerations. Moreover, many such pipeline vessels are located in outlying areas witl1 no on-site attendant, and thel-erore a reliable device and method for remote detection is necessary and desirable.
If, on the other hand, such devices and methods indicate erroneously that a leakor break has occurred, a false alarm is sounded. False alarms can be expensive to the pipeline operator, as they could cause false shut-downs of the pipeline and/or unneces-sary repair trips by maintenance persolmel. Therefore, while it is desirable to provide a device and method that is sensitive to detection of those vessel characteristics whose magnitude change upon the occurrence o~ a leak or break (such as pres~ule, flow and tel~per~lule), care must be taken to preclude false detection possibilities.
Currently available leak detection devices, such as the pressure based sensing device disclosed in U.S. Patent No. 4,012,944, can be sensitive enough to detect most unacceptable operational conditions, but they do not have an accurate method of determining if the unacceptable condition results from something other than a leak or break, and therefore the potential for false alarms exists. Devices as this measure pressure and calculate both rate of pressure change and total pressure cllange, and from these measurements determine if a leak or break has occurred.
Moreover, most commercially available devices for detection of pipeline leaks or breaks are at least in part mechanical in nature, often giving rise to such problems as a lack of sufficient sensitivity, and greater susceptibility to corrosion, condensation and blockage.
Comparison of rates of change at successive preselected timed intervals has beenfound to greatly facilitate recognition of instances of false triggering and theavoidance of false alarms without the sacrifice of sufficient sensitivity to detect substantially all leaks and breaks, particularly when utilized in conjunction with known leak and break detection techniques. Also, this method of operation may beimplemented wholly electronically, avoiding the difficulties that may plague devices with mechanical components, and using any desired characteristic, of course including the most common characteristic of pressure.
SUMMARY OF THE INVENTION
It is, therefore, an object of the present invention to provide a device and method for detecting leaks or breaks in pressurized fluid vessels, such as a pipeline, which minimi7.es or elimin~tes false alarms.
It is another object of the present invention to provide a device and method, asset forth above, that measures a cllaracteristic that changes upon the occurrence of a break or leak, determines the rate of change of such characteristic at preselected times, and compares the rates of change at successive preselected timed intervals.
It is yet another object of the present invention to provide a device and method, as set forth above, that also determines the total change, and minimum and maximum magnitudes of such characteristic in the vessel over a preselected period of time.
It is still another object of the present invention to provide a device and method, as set forth above, that may be implemented electronically so as to enhance sensitivity and minimi7.~. or eliminate susceptibility to corrosion, condensation and blockage.
It is a further object of the present invention to provide a device and method, as set forth above, that utilizes pressure as the characteristic from which determinations as to leaks or breaks is made.
It is yet a further object of the present invention to provide a device and method, as above, in which the fluid present can be eitller gaseous or liquid in nature.
It is still another object of the present invention to provide a device and method, as set forth above, that can be utilized in a similar manner with other fluid character-S istics in addition to pressure, such as flow or temperature.
These and other objects and advantages of the present invention over existingprior art forms will become more apparent and fully understood from the following description in conjunction with the accompanying drawings.
In general, a device for monitoring and detecting irregularities in a preselected 10 characteristic of a fluid in a vessel includes transducer means for monitoring the preselected characteristic of the fluid in the vessel and providing an analog transducer output signal proportional thereto, converter means for receiving the analog transducer output signal, sampling the analog transducer output signal at preselected measure-ment time intervals within a preselected study time interval, and providing a digital 15 output signal proportional to the analog transducer output signal at each preselected measurement time interval, and a processor means. The processor means receives the digital output signal for each preselected measurement time interval, calculates a plurality of changes in the preselected characteristic for a like plurality of preselected measurement time intervals, calculates a total change in the preselected characteristic 20 over the preselected study time interval, compales the plurality of changes in the preselected characteristic to a preselected maximum rate of change in the preselected characteristic, compares the total change in the preselected characteristic over the preselected study time interval to a preselected maximum total change in the pre-selected characteristic, and generates an alarm output signal when a preselected25 plurality of the plurality of changes in the preselected characteristic exceed the preselected maximum rate of change in the preselected characteristic and the total change in the preselected characteristic over the preselected study time interval exceeds the preselected maximum total change in the preselected characteristic for longer than a first preselected period of time. An alarm receives the alarm output 30 signal and annunciates the existence of an irregularity in the preselected characteristic In general, a method for monitoring and detecting irregularities in a preselected characteristic of a fluid in a vessel includes the steps of monitoring the preselected characteristic of the fluid in the vessel and providing an analog transducer output __ -- 4 --signal proportional thereto, sampling the analog transducer output signal at preselected mea~ .ent time intervals within a preselected study time interval and providing a digital output.signal proportional to the analog transducer output signal at each preselected measurement time interval, calculating a plurality of changes in thepreselected characteristic for a like plurality of the preselected measurement time intervals, calculating a total change in the preselected characteristic over the preselect-ed study time interval, comparing the plurality of changes in the preselected character-istic to a preselected maximum rate of change in the preselected characteristic, com-paring the total change in the preselected characteristic over the preselected study time interval to a preselected maximum total change in the preselected characteristic, gen-erating an alarm output signal when a preselected plurality of the plurality of changes in the preselected characteristic exceed the preselected maximum rate of change in the preselected characteristic and the total change in the preselected characteristic over the preselected study time interval exceeds the preselected maximum total change in the preselected characteristic for longer than a first preselected period of time, and, annunciating the existence of an irregularity in the preselected characteristic.
BRIEF DESCRIPTION OF THE~l)RAWINGS
Fig. 1 is a block diagram of an exemplary device in accordance with the con-cept of the present inventioll for use with a pressurized fluid vessel such as a pipeline.
Fig. 2 is a plot of exemplary pressure magnitude as a function of time within a typical pipeline. Nine instantaneous pressure data points, identified as PA through P~, present pressure after eight equal duration preselected time intervals, such as eight seconds each. However, as illustrated, both pressure and time are relative and not intended to be drawn to a specific scale.
Fig. 3 is a top level flow chart of the operation of the device and particularly, the microcomputer.
PREFERRED EMBODIMENT FOR CARRYING OUT THE INVENTION
Fig. I depicts a device, generally indicated by the numeral 10, and performs a method for detecting unacceptable operational conditions (also called irregular operation) in a pressurized fluid vessel such as a pipeline 20. Device 10 includes a tr~n~dllcer 21, a signal conditioner and analog-to-digital (A/D) converter 22, a micro-__ -- 5 --computer 23, memory 26 such as program ROM 27 and non-volatile data memory 28, wake-up timer 29, alarm 30, and where desired, a system shut-down actuator such as valve shut-off actuator 31.
Transducer 21 may be any measuring instrument capable of withstanding the enviromnental rigors of pipeline 20, monitoring the instantaneous pipeline character-istic responsive to leaks and breaks of interest (in the preferred embodiment, instan-taneous pre~u~e), and generating a proportional electrical output signal. The pressure signal is received by A/D converter 22, which digitizes and samples as appropriate for the application and as requested by microcomputer 23. In the present example it has been found sufficient and optimal to collect and store pl~S:iUI~ magnitude at every eight seconds for eight intervals of time. This yields the nine instantaneous pressure data points, identified as PA through P" in Fig. 2, collected over a sixty-four second period of time.
Microcomputer 23 may be any processor capable of performing the necessary operation described in further detail hereinafter. However, inasmuch as power iscommonly limited at the remote pipeline 20 sites where device 10 is installed, it is preferable for this processor to include a so-called idle and powerdown feature and on-board memory and I/O to conserve energy consumption and reduce component count and expense. The Model 80C31 CHMOS Single-Chip 8-bit Microcomputer commercially available from Intel Corporation of Santa Clara, California has been found to be suitable for inclusion as microcomputer 23. Supporting microcomputer23 is memory 26 having conventional program ROM 27 and non-volatile data memory 28, and a wake-up timer 29 that actuates microcomputer 23 at preselected intervals for performance of its programmed functions.
Microcomputer 23 generates an appropriate alarm signal to alarm 30, and optionally to actuator 31 upon the occurrence of an unacceptable operation condition as noted furtl~er hereinafter. Alarm 30, which may be visual and/or audible, andactuator 31 are further described in U.S. Patent No. 4,012,944.
Operation of device 10 may be most readily understood by reference to the exemplary graph of pressure with time shown in Fig. 2, and the flow-chart of Fig. 3.
Microcomputer 23 performs a plurality of distinctly different tests upon the collected pressure data to reliably ascertain if a leak or break in pipeline 20 has occurred. The first test, which may be referred to as timed interval comparisons, involves a - 6 - 212991~
._ comparison of rates of change of ples~ure at successive preselected timed intervals (called preselected measurement time intervals).
The timed interval comparisons test begins by calculatin~ the timed interval pressure changes throughout a preselected study time interval. Faulty results may be minimi7.ed by considering the timed interval to be more than one data sample period.
Thus, in the present example, it is advantageous to pair every four pressure measure-ment and calculate the following timed interval pressure changes: PE-PA~ PF-P~, PG r~
and Pl-PE- The total change hl pressure, Pl-P,~, is also calculated. Each of the timed interval pressure changes are compared to a preselected maximum rate of pressurechange (dP/dt(max)), and the total change in pressure is compared to a preselected maximum total change in pressure. If each of the timed interval pressure changesexceed the preselected maximum rate of pressure change (dP/dt(max)), and the total change in pressure exceeds the preselected maximum total change in pressure for longer than a first preselected period of time (Tl), microcomputer 23 actuates alarm 30 and/or actuator 31 as previously noted.
Microcomputer 23 may, and preferably does, also perform other calculations and tests upon the collected pressure data. For example, the average pressure throughout the timed intervals can be summed and averaged (e.g., (PF+P~1+PH+PI)/4)~
and compared to both preselected maximum and minimum pressure changes. If the average pressure change exceeds the preselected maximum pressure change for longer than a preselected period of time (T2), or the average pressure change is less than the preselected minimum pressure change for longer than a preselected period of time(T3), microcomputer 23 may actuate alarm 30 and/or actuator 31 as yreviously noted.
Tests such as these are described more fully in U.S. Patent No. 4,012,944, which is hereby incorporated by reference.
Turning to the flow chart presented in Fig. 3, operation of device 10 can be seen to begin in step 40 with reset of microcomputer 23 by wake-up timer at the preselected time intervals (here, every eight seconds). Thereafter microcomputer 23 performs in step 41 any necessary or desired initialization as would be known to the ordinarily skilled artisan, activates in step 42 transducer 21 and A/D converter 22, and initiates measurement in step by transducer 21 of instantaneous pressure in pipeline 20. Next microcomputer 23 performs in step 46 the test calculations described hereinbefore, pelrol.ns in step 47 the previously noted comparisons to ascertain if 7 212991~
there exists a leak or break, and, if so, activates in step 48 alarm 30 and/or actuator 31.
It has been found helpful in monitoring pipeline performance and selecting optimal threshold values to record pressure data for later study for a limited period of 5 time such as 30 rninutes, every time the instantaneous ple~ule or change in pressure exceeds some preselected limits that are not as great as those indicative of a break or leak condition. To this end, microcomputer 30 may perform in step 50 whatever further comparisons are desired to conclude whetl~er data should be logged, and if those comparisons are positive, collect data in step 51 for the preselected period of 10 time interval. If the data collection limits are not exceeded, and optionally but desirably between collection of data durirlg the study interval, microcomputer 52 goes into its so-called powerdown mode as shown in step 52.
Inasmuch as the present invention is subject to variations, modifications and changes in detail, some of which have been expressly stated herein, it is intended that 15 all matter described througllout this entire specification or shown in the accompanying drawings be interpreted as illustrative and not in a limiting sense. It should thus be evident that a device constructed and method perfornned according to the concept of the present invention, and reasonably equivalent thereto, will accomplish the objects of the present invention and otherwise substantially improve the art of detection of 20 unacceptable operation conditions in pressurized fluid vessels.
It is still another object of the present invention to provide a device and method, as set forth above, that can be utilized in a similar manner with other fluid character-S istics in addition to pressure, such as flow or temperature.
These and other objects and advantages of the present invention over existingprior art forms will become more apparent and fully understood from the following description in conjunction with the accompanying drawings.
In general, a device for monitoring and detecting irregularities in a preselected 10 characteristic of a fluid in a vessel includes transducer means for monitoring the preselected characteristic of the fluid in the vessel and providing an analog transducer output signal proportional thereto, converter means for receiving the analog transducer output signal, sampling the analog transducer output signal at preselected measure-ment time intervals within a preselected study time interval, and providing a digital 15 output signal proportional to the analog transducer output signal at each preselected measurement time interval, and a processor means. The processor means receives the digital output signal for each preselected measurement time interval, calculates a plurality of changes in the preselected characteristic for a like plurality of preselected measurement time intervals, calculates a total change in the preselected characteristic 20 over the preselected study time interval, compales the plurality of changes in the preselected characteristic to a preselected maximum rate of change in the preselected characteristic, compares the total change in the preselected characteristic over the preselected study time interval to a preselected maximum total change in the pre-selected characteristic, and generates an alarm output signal when a preselected25 plurality of the plurality of changes in the preselected characteristic exceed the preselected maximum rate of change in the preselected characteristic and the total change in the preselected characteristic over the preselected study time interval exceeds the preselected maximum total change in the preselected characteristic for longer than a first preselected period of time. An alarm receives the alarm output 30 signal and annunciates the existence of an irregularity in the preselected characteristic In general, a method for monitoring and detecting irregularities in a preselected characteristic of a fluid in a vessel includes the steps of monitoring the preselected characteristic of the fluid in the vessel and providing an analog transducer output __ -- 4 --signal proportional thereto, sampling the analog transducer output signal at preselected mea~ .ent time intervals within a preselected study time interval and providing a digital output.signal proportional to the analog transducer output signal at each preselected measurement time interval, calculating a plurality of changes in thepreselected characteristic for a like plurality of the preselected measurement time intervals, calculating a total change in the preselected characteristic over the preselect-ed study time interval, comparing the plurality of changes in the preselected character-istic to a preselected maximum rate of change in the preselected characteristic, com-paring the total change in the preselected characteristic over the preselected study time interval to a preselected maximum total change in the preselected characteristic, gen-erating an alarm output signal when a preselected plurality of the plurality of changes in the preselected characteristic exceed the preselected maximum rate of change in the preselected characteristic and the total change in the preselected characteristic over the preselected study time interval exceeds the preselected maximum total change in the preselected characteristic for longer than a first preselected period of time, and, annunciating the existence of an irregularity in the preselected characteristic.
BRIEF DESCRIPTION OF THE~l)RAWINGS
Fig. 1 is a block diagram of an exemplary device in accordance with the con-cept of the present inventioll for use with a pressurized fluid vessel such as a pipeline.
Fig. 2 is a plot of exemplary pressure magnitude as a function of time within a typical pipeline. Nine instantaneous pressure data points, identified as PA through P~, present pressure after eight equal duration preselected time intervals, such as eight seconds each. However, as illustrated, both pressure and time are relative and not intended to be drawn to a specific scale.
Fig. 3 is a top level flow chart of the operation of the device and particularly, the microcomputer.
PREFERRED EMBODIMENT FOR CARRYING OUT THE INVENTION
Fig. I depicts a device, generally indicated by the numeral 10, and performs a method for detecting unacceptable operational conditions (also called irregular operation) in a pressurized fluid vessel such as a pipeline 20. Device 10 includes a tr~n~dllcer 21, a signal conditioner and analog-to-digital (A/D) converter 22, a micro-__ -- 5 --computer 23, memory 26 such as program ROM 27 and non-volatile data memory 28, wake-up timer 29, alarm 30, and where desired, a system shut-down actuator such as valve shut-off actuator 31.
Transducer 21 may be any measuring instrument capable of withstanding the enviromnental rigors of pipeline 20, monitoring the instantaneous pipeline character-istic responsive to leaks and breaks of interest (in the preferred embodiment, instan-taneous pre~u~e), and generating a proportional electrical output signal. The pressure signal is received by A/D converter 22, which digitizes and samples as appropriate for the application and as requested by microcomputer 23. In the present example it has been found sufficient and optimal to collect and store pl~S:iUI~ magnitude at every eight seconds for eight intervals of time. This yields the nine instantaneous pressure data points, identified as PA through P" in Fig. 2, collected over a sixty-four second period of time.
Microcomputer 23 may be any processor capable of performing the necessary operation described in further detail hereinafter. However, inasmuch as power iscommonly limited at the remote pipeline 20 sites where device 10 is installed, it is preferable for this processor to include a so-called idle and powerdown feature and on-board memory and I/O to conserve energy consumption and reduce component count and expense. The Model 80C31 CHMOS Single-Chip 8-bit Microcomputer commercially available from Intel Corporation of Santa Clara, California has been found to be suitable for inclusion as microcomputer 23. Supporting microcomputer23 is memory 26 having conventional program ROM 27 and non-volatile data memory 28, and a wake-up timer 29 that actuates microcomputer 23 at preselected intervals for performance of its programmed functions.
Microcomputer 23 generates an appropriate alarm signal to alarm 30, and optionally to actuator 31 upon the occurrence of an unacceptable operation condition as noted furtl~er hereinafter. Alarm 30, which may be visual and/or audible, andactuator 31 are further described in U.S. Patent No. 4,012,944.
Operation of device 10 may be most readily understood by reference to the exemplary graph of pressure with time shown in Fig. 2, and the flow-chart of Fig. 3.
Microcomputer 23 performs a plurality of distinctly different tests upon the collected pressure data to reliably ascertain if a leak or break in pipeline 20 has occurred. The first test, which may be referred to as timed interval comparisons, involves a - 6 - 212991~
._ comparison of rates of change of ples~ure at successive preselected timed intervals (called preselected measurement time intervals).
The timed interval comparisons test begins by calculatin~ the timed interval pressure changes throughout a preselected study time interval. Faulty results may be minimi7.ed by considering the timed interval to be more than one data sample period.
Thus, in the present example, it is advantageous to pair every four pressure measure-ment and calculate the following timed interval pressure changes: PE-PA~ PF-P~, PG r~
and Pl-PE- The total change hl pressure, Pl-P,~, is also calculated. Each of the timed interval pressure changes are compared to a preselected maximum rate of pressurechange (dP/dt(max)), and the total change in pressure is compared to a preselected maximum total change in pressure. If each of the timed interval pressure changesexceed the preselected maximum rate of pressure change (dP/dt(max)), and the total change in pressure exceeds the preselected maximum total change in pressure for longer than a first preselected period of time (Tl), microcomputer 23 actuates alarm 30 and/or actuator 31 as previously noted.
Microcomputer 23 may, and preferably does, also perform other calculations and tests upon the collected pressure data. For example, the average pressure throughout the timed intervals can be summed and averaged (e.g., (PF+P~1+PH+PI)/4)~
and compared to both preselected maximum and minimum pressure changes. If the average pressure change exceeds the preselected maximum pressure change for longer than a preselected period of time (T2), or the average pressure change is less than the preselected minimum pressure change for longer than a preselected period of time(T3), microcomputer 23 may actuate alarm 30 and/or actuator 31 as yreviously noted.
Tests such as these are described more fully in U.S. Patent No. 4,012,944, which is hereby incorporated by reference.
Turning to the flow chart presented in Fig. 3, operation of device 10 can be seen to begin in step 40 with reset of microcomputer 23 by wake-up timer at the preselected time intervals (here, every eight seconds). Thereafter microcomputer 23 performs in step 41 any necessary or desired initialization as would be known to the ordinarily skilled artisan, activates in step 42 transducer 21 and A/D converter 22, and initiates measurement in step by transducer 21 of instantaneous pressure in pipeline 20. Next microcomputer 23 performs in step 46 the test calculations described hereinbefore, pelrol.ns in step 47 the previously noted comparisons to ascertain if 7 212991~
there exists a leak or break, and, if so, activates in step 48 alarm 30 and/or actuator 31.
It has been found helpful in monitoring pipeline performance and selecting optimal threshold values to record pressure data for later study for a limited period of 5 time such as 30 rninutes, every time the instantaneous ple~ule or change in pressure exceeds some preselected limits that are not as great as those indicative of a break or leak condition. To this end, microcomputer 30 may perform in step 50 whatever further comparisons are desired to conclude whetl~er data should be logged, and if those comparisons are positive, collect data in step 51 for the preselected period of 10 time interval. If the data collection limits are not exceeded, and optionally but desirably between collection of data durirlg the study interval, microcomputer 52 goes into its so-called powerdown mode as shown in step 52.
Inasmuch as the present invention is subject to variations, modifications and changes in detail, some of which have been expressly stated herein, it is intended that 15 all matter described througllout this entire specification or shown in the accompanying drawings be interpreted as illustrative and not in a limiting sense. It should thus be evident that a device constructed and method perfornned according to the concept of the present invention, and reasonably equivalent thereto, will accomplish the objects of the present invention and otherwise substantially improve the art of detection of 20 unacceptable operation conditions in pressurized fluid vessels.
Claims (10)
1. A device for monitoring and detecting irregularities in a preselected characteristic of a fluid in a vessel, comprising:
transducer means for monitoring the preselected characteristic of the fluid in the vessel and providing an analog transducer output signal proportional thereto;
converter means for receiving said analog transducer output signal, sampling said analog transducer output signal at preselected measurement time intervals within a preselected study time interval, and providing a digital output signal proportional to said analog transducer output signal at each said preselected measurement time interval;
processor means for receiving said digital output signal for each said preselected measurement time interval, calculating a plurality of changes in thepreselected characteristic for a like plurality of said preselected measurement time intervals, calculating a total change in the preselected characteristic over said preselected study time interval, comparhlg said plurality of changes in the preselected characteristic to a preselected maximum rate of change in the preselected characteris-tic, comparing said total change in the preselected characteristic over said preselected study time interval to a preselected maximum total change in the preselected charac-teristic, and generating an alarm output signal when a preselected plurality of said plurality of changes in the preselected characteristic exceed said preselected maximum rate of change in the preselected characteristic and said total change in the preselected characteristic over said preselected study time interval exceeds said preselected maximum total change in the preselected characteristic for longer than a first preselected period of time; and, alarm means receiving said alarm output signal and annunciating the existence of an irregularity in the preselected characteristic.
transducer means for monitoring the preselected characteristic of the fluid in the vessel and providing an analog transducer output signal proportional thereto;
converter means for receiving said analog transducer output signal, sampling said analog transducer output signal at preselected measurement time intervals within a preselected study time interval, and providing a digital output signal proportional to said analog transducer output signal at each said preselected measurement time interval;
processor means for receiving said digital output signal for each said preselected measurement time interval, calculating a plurality of changes in thepreselected characteristic for a like plurality of said preselected measurement time intervals, calculating a total change in the preselected characteristic over said preselected study time interval, comparhlg said plurality of changes in the preselected characteristic to a preselected maximum rate of change in the preselected characteris-tic, comparing said total change in the preselected characteristic over said preselected study time interval to a preselected maximum total change in the preselected charac-teristic, and generating an alarm output signal when a preselected plurality of said plurality of changes in the preselected characteristic exceed said preselected maximum rate of change in the preselected characteristic and said total change in the preselected characteristic over said preselected study time interval exceeds said preselected maximum total change in the preselected characteristic for longer than a first preselected period of time; and, alarm means receiving said alarm output signal and annunciating the existence of an irregularity in the preselected characteristic.
2. A device, as set forth in claim 1, wherein said processor means further includes means for calculating the average value of the preselected characteristic for each said preselected measurement time interval over said preselected study timeinterval, comparing said average value to a preselected maximum value of the presel-ected characteristic and a preselected minimum value of the preselected characteristic, and generating said alarm output signal when said average value exceeds at least one of said preselected maximum value and said preselected minimum value.
3. A device, as set forth in claim 2, wherein said processor means further includes means for limiting power consumption during periods between processing intervals, and further including wake-up timer means for periodically initiatingresumption of processor processing at said preselected measurement time intervals within said preselected study time interval.
4. A device, as set forth in claim 3, wherein the preselected characteristic is pressure, the vessel is a pipeline, and said transducer means monitors pressure.
5. A device, as set forth in claim 3, wherein said alarm means includes means for actuating corrective action to at least minimize the effects of the irregularity in the preselected characteristic.
6. A method for monitoring and detecting irregularities in a preselected character-istic of a fluid in a vessel, comprising the steps of:
monitoring the preselected characteristic of the fluid in the vessel and providing an analog transducer output signal proportional thereto;
sampling said analog transducer output signal at preselected measurement time intervals within a preselected study time interval and providing a digital output signal proportional to said analog transducer output signal at each preselected measurement time interval;
calculating a plurality of changes in the preselected characteristic for a like plurality of said preselected measurement time intervals;
calculating a total change in the preselected characteristic over said preselected study time interval;
comparing said plurality of changes in the preselected characteristic to a preselected maximum rate of change in the preselected characteristic;
comparing said total change in the preselected characteristic over said preselected study time interval to a preselected maximum total change in the preselected characteristic;
generating an alarm output signal when a preselected plurality of said pluralityof changes in the preselected characteristic exceed said preselected maximum rate of change in the preselected characteristic and said total change in the preselected characteristic over said preselected study time interval exceeds said preselected maximum total change in the preselected characteristic for longer than a first preselected period of time; and, annunciating the existence of an irregularity in the preselected characteristic.
monitoring the preselected characteristic of the fluid in the vessel and providing an analog transducer output signal proportional thereto;
sampling said analog transducer output signal at preselected measurement time intervals within a preselected study time interval and providing a digital output signal proportional to said analog transducer output signal at each preselected measurement time interval;
calculating a plurality of changes in the preselected characteristic for a like plurality of said preselected measurement time intervals;
calculating a total change in the preselected characteristic over said preselected study time interval;
comparing said plurality of changes in the preselected characteristic to a preselected maximum rate of change in the preselected characteristic;
comparing said total change in the preselected characteristic over said preselected study time interval to a preselected maximum total change in the preselected characteristic;
generating an alarm output signal when a preselected plurality of said pluralityof changes in the preselected characteristic exceed said preselected maximum rate of change in the preselected characteristic and said total change in the preselected characteristic over said preselected study time interval exceeds said preselected maximum total change in the preselected characteristic for longer than a first preselected period of time; and, annunciating the existence of an irregularity in the preselected characteristic.
7. A method, as set forth in claim 6, further including the steps of calculating the average value of the preselected characteristic for each said preselected measurement time interval over said preselected study time interval, comparing said average value to a preselected maximum value of the preselected characteristic and a preselected minimum value of the preselected characteristic, and generating said alarm output signal when said average value exceeds at least one of said preselected maximum value and said preselected minimum value.
8. A method, as set forth in claim 7, wherein said steps of calculating a plurality of changes, calculating a total change, comparing said plurality of changes, comparing said total change, and generating an alarm output signal all occur in a processor having a powerdown operation mode for limiting power consumption during periods between processing intervals, and further including the step of periodically initiating resumption of processor processing at said preselected measurement time intervals within said preselected study time interval.
9. A method, as set forth in claim 8, wherein said step of monitoring a preselected characteristic includes the step of monitoring pressure in a pipeline.
10. A method, as set forth in claim 9, further including the step of actuating corrective action to at least minimize the effects of the irregularity in the preselected characteristic.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US08/118,181 | 1993-09-09 | ||
| US08/118,181 US5361622A (en) | 1993-09-09 | 1993-09-09 | Device and method for detection of leaks in pressurized fluid vessels |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2129915A1 CA2129915A1 (en) | 1995-03-10 |
| CA2129915C true CA2129915C (en) | 1995-10-17 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002129915A Expired - Fee Related CA2129915C (en) | 1993-09-09 | 1994-08-11 | Device and method for detection of leaks in pressurized fluid vessels |
Country Status (2)
| Country | Link |
|---|---|
| US (1) | US5361622A (en) |
| CA (1) | CA2129915C (en) |
Families Citing this family (26)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB9302958D0 (en) * | 1993-02-13 | 1993-03-31 | Lucas Ind Plc | Method of and apparatus for detecting fuel system leak |
| US5526679A (en) * | 1995-01-05 | 1996-06-18 | Campo/Miller | Automatically calibrated pressurized piping leak detector |
| GB2306671B (en) * | 1995-10-19 | 2000-03-15 | British Gas Plc | Method and apparatus for testing a fluid conduit system for leaks |
| US6311548B1 (en) * | 1999-08-25 | 2001-11-06 | Delphi Technologies, Inc. | Method of validating a diagnostic leak detection test for a fuel tank |
| AU2001259373B2 (en) * | 2000-05-02 | 2005-10-06 | Vista Precision Solutions, Inc. | Improved methods for detecting leaks in pressurized piping with a pressure measurement system |
| CA2416171A1 (en) * | 2003-01-13 | 2004-07-13 | Pure Technologies Ltd. | Pipeline monitoring system |
| US6880383B2 (en) * | 2003-05-14 | 2005-04-19 | General Motors Corporation | Apparatus and method for fuel vapor leak detection |
| US20050067895A1 (en) * | 2003-09-25 | 2005-03-31 | Marathe Sameer S. | Apparatus and method of monitoring braking system pressure |
| US7292954B2 (en) * | 2004-07-28 | 2007-11-06 | Hr Textron Inc. | Acceptance testing of actuators using backlash and stiction measurements |
| US20060260691A1 (en) * | 2005-05-20 | 2006-11-23 | Davidoff John A | Systems and methods for detecting and preventing fluid leaks |
| GB2423562B (en) * | 2005-05-27 | 2007-01-17 | Brinker Technology Ltd | Determining leak location and size in pipes |
| CN100449199C (en) * | 2006-08-30 | 2009-01-07 | 姬文超 | Safety early warning system for monitoring corrosion, leakage of pipeline on active service, and control method |
| US7438060B2 (en) * | 2006-11-17 | 2008-10-21 | General Motors Corporation | System for detecting purge valve malfunction |
| US20080169072A1 (en) * | 2007-01-12 | 2008-07-17 | Cascades Canada Inc. | Wet Embossed Paperboard and Method and Apparatus for Manufacturing Same |
| US8012309B2 (en) * | 2007-01-12 | 2011-09-06 | Cascades Canada Ulc | Method of making wet embossed paperboard |
| US10352505B2 (en) | 2008-06-27 | 2019-07-16 | Exxonmobil Research And Engineering Company | Method and apparatus for real time enhancing of the operation of a fluid transport pipeline |
| CN102132138B (en) * | 2008-06-27 | 2015-06-17 | 埃克森美孚研究工程公司 | A method and apparatus for real time enhancing of the operation of a fluid transport pipeline |
| US8332130B2 (en) * | 2008-09-30 | 2012-12-11 | Dale Arden Stretch | Leak detection system |
| CN102235575B (en) * | 2010-04-29 | 2013-12-25 | 国际商业机器公司 | Data processing method and system for checking pipeline leakage |
| CN102305646A (en) * | 2011-05-10 | 2012-01-04 | 安徽润尔兴仪表有限公司 | Intelligent anti-leakage electromagnetic flowmeter |
| GB2551378A (en) * | 2016-06-16 | 2017-12-20 | Bentley Motors Ltd | Method of assessing damage to composite members |
| WO2018052675A1 (en) | 2016-09-19 | 2018-03-22 | Exxonmobil Research And Engineering Company | A method and apparatus for real time enhancing of the operation of a fluid transport pipeline |
| JP6958487B2 (en) * | 2018-06-05 | 2021-11-02 | 三菱電機ビルテクノサービス株式会社 | Elevator device |
| US11774312B2 (en) | 2018-12-18 | 2023-10-03 | Rockwool A/S | Method for testing and for an inspection of a functionality of an insulation work on industrial installations, especially of an insulation surrounding a pipe; system comprising a pipe especially for transport of cooled media, and insulation for such a pipe |
| KR102208146B1 (en) * | 2019-05-23 | 2021-01-27 | 삼인싸이언스(주) | Gas leak monitoring system |
| DE102022203196B4 (en) | 2022-03-31 | 2024-02-29 | Vitesco Technologies GmbH | Method for determining the functionality of a pressure sensor and battery arrangement |
Family Cites Families (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE1922986C3 (en) * | 1969-05-06 | 1975-09-18 | Erdoel-Raffinerie Mannheim Gmbh, 6800 Mannheim | Procedure for monitoring leaks in liquid lines |
| US3903729A (en) * | 1970-12-30 | 1975-09-09 | Taft Broadcasting Corp | Method and apparatus for detecting a break or other occurrence in a pipeline containing gas under pressure |
| US3884077A (en) * | 1973-06-01 | 1975-05-20 | Southwestern Manufacturing Co | Rate of pressure change sensing system |
| US4012944A (en) * | 1974-12-09 | 1977-03-22 | Shafer Valve Company | Electronic fluid pipeline leak detector and method |
| EP0094533B1 (en) * | 1982-05-15 | 1986-03-12 | Fried. Krupp Gesellschaft mit beschränkter Haftung | Method for leakage testing of pipes or networks of pipes |
| US4625545A (en) * | 1985-04-05 | 1986-12-02 | Testrite, Inc. | Method and apparatus for detecting leaks |
| US4837707A (en) * | 1986-12-24 | 1989-06-06 | Emhart Industries, Inc. | Container inspection apparatus |
| US4796466A (en) * | 1987-02-17 | 1989-01-10 | Ed Farmer | System for monitoring pipelines |
| US4835717A (en) * | 1987-12-18 | 1989-05-30 | Emhart Industries, Inc. | Intelligent line pressure probe |
| US5272646A (en) * | 1991-04-11 | 1993-12-21 | Farmer Edward J | Method for locating leaks in a fluid pipeline and apparatus therefore |
-
1993
- 1993-09-09 US US08/118,181 patent/US5361622A/en not_active Expired - Fee Related
-
1994
- 1994-08-11 CA CA002129915A patent/CA2129915C/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| US5361622A (en) | 1994-11-08 |
| CA2129915A1 (en) | 1995-03-10 |
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